Among typical dental materials are dental fillings, dental adhesives, dental prostheses, and dental prosthesis repair materials. The dental fillings are materials for filling in holes which have been bored or drilled for treatment of decayed teeth. The dental prostheses are artificial materials (crowns, dentures) for restoration of defective teeth. The dental prosthesis repair materials refer to materials for repairing the above prostheses, and their examples include repair materials for tooth crowns, and repair materials for denture base materials.
An overwhelming number of such dental materials are composed of a plurality of components, and a plurality of the materials are mixed in situ and used by dentists or the like during treatment of patients. Combinations of these materials include combinations of liquid materials, combinations of powder materials and liquid materials, and combinations of paste materials.
Of these combinations, a combination of a powder material and a liquid material (a dental powder/liquid material) can utilize a sharp increase in viscosity produced by mixing the powder material and the liquid material. Generally, it is important for dental treatment that the treatment is completed promptly within a dental examination room (so as not to make the patient wait). Thus, it is important for the above material to be excellent in properties, such as shapability, appropriate property for building up with resin (handleability), and a quick finish (final change), as a dental material. Since these properties can be obtained by utilizing the above-mentioned sharp viscosity increase, the rapidity of the viscosity increase of the dental powder/liquid material is an important characteristic.
Typical examples of a powder material/liquid material combination among such dental powder/liquid materials are denture base liners, dental repair resins, tissue conditioners, and dental resin cements.
The denture base liner is a repair material which, when a denture mounted does not fit the oral mucosa because of bone resorption, deformation of the mucosal surface, or the like, liners the surface of the unfit denture base to render the denture fitting again.
The dental repair resin is a resin material for repairing a prosthesis, such as a fractured denture or a chipped artificial tooth, or for preparing a temporary crown for use temporarily at a defective site.
The tissue conditioner is a tacky conditioning material which, when the gingival mucosa hurts, for example, because a denture does not fit, is used in an area of close contact between the denture and the gingiva for recovery of the gingival mucosa. The tissue conditioner takes a final form of an elastic body under the conditions for its use.
The dental resin cement is a material which, in restoring a tooth having lost functions owing to a dental caries, an accident or the like, with the use of a metallic or ceramic material for crown restoration, called an inlay or crown, is used to fix the material for crown restoration to the tooth. This material is intended for firm adhesion of various adherends (metals, ceramics, etc.) as well as the tooth.
As the denture base liner and the dental repair resin, two-component materials composed of the following components, for example, are generally used: polymeric organic components such as polymethyl methacrylate (hereinafter also referred to as PMMA) polyethyl methacrylate (hereinafter also referred to as PEMA), and a copolymer of methyl methacrylate and ethyl methacrylate (hereinafter also referred to as P(MMA-EMA)); and monomer components such as radical polymerizable compounds, e.g., methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-hydroxyethyl methacrylate.
Such a two-component material is composed of a powder material containing an organic polymer and a liquid material containing a monomer, and can be prepared by distributing a suitable polymerization initiator component. A radical polymerization initiator is frequently used as the polymerization initiator component for curing. Both types of components are mixed during dental examination, and the monomer is polymerized using the radical polymerization initiator, whereby a cured product can be obtained. When the monomer component used in the above two-component material is brought into contact with the polymer component, it dissolves a part of the polymer component in a short time and infiltrates into the polymer component to swell it. Thus, the viscosity of a mixture of the monomer component and the polymer component is moderately adjusted, whereby the advantage that a clinical or technical operation can be facilitated is produced (see Patent Document 1).
As the above-mentioned two-component materials, there are not only finally rigid cured products, but also finally elastic bodies like the denture base tissue conditioners. In this case, as the liquid materials, plasticizers in liquid form, typified by sebacic acid ester and phthalic acid ester, are used rather than monomers. High-molecular plasticizers are also used satisfactorily as the liquid plasticizers (see Patent Document 2).
Patent Document 3 discloses a flat bag comprising a film and having a partition portion nearly in the middle, wherein a dry nonwoven fabric is accommodated in one of the resulting compartments, while a cosmetic such as a facial lotion can be accommodated separately in the other compartment. The partition portion of the flat bag is formed by thermally fusing upper and lower parts of the film, which constitute the upper and lower surfaces of the bag, via a strip-shaped tape having releasability. Such a flat bag is configured such that the partition wall is ruptured, whereby the accommodation compartments communicate with each other, with the result that the nonwoven fabric is adequately infiltrated with the facial lotion.